When operating in a hostile environment, an airborne vehicle often uses a radar electronic surveillance system (RESS) to determine the presence of (possibly unfriendly) probe signals from a threat radar system (TRS), which may be ground-based, water-based or air-based. If such a probe signal is identified, the RESS, at best, is able to determine the relative bearing of the TRS from the present airborne vehicle location. This relative bearing information is sufficient to alert the airborne vehicle occupants to presence of a radar interrogation threat but does not, by itself, allow determination of the present location and/or velocity of the TRS. Lacking additional information, the airborne vehicle can only determine the general direction of the source of the TRS probe signals.
What is needed is an approach that allows an airborne vehicle with RESS to determine the present location of, distance to, and/or velocity of, a TRS facility that is transmitting probe signals. Preferably, this approach should allow determination of the location, distance and/or velocity in real time and relatively quickly and should allow flexibility in choice of the information used to determine the location, distance and/or velocity.